Last summer, AT&T introduced new data plans around the same time as the new iPhone 4 launch. Because heavy data users were bogging down AT&T’s network, two limited plans took the place of unlimited data options – 2GB or 250MB. It wasn’t the most pleasant change, but those who had unlimited data plans on contract were grandfathered in. Now with the Verizon iPhone on the horizon, and the new carrier’s promise to offer unlimited data plans, AT&T might be giving some users the option to go back to all-you-can-eat broadband.

The Wall Street Journal reports:

Jose Argumedo, of Brentwood, N.Y., says he and a friend were switched to an unlimited plan recently after they called AT&T’s customer service. Both have iPhone 4s, and previously had earlier iPhone models.

“We handle customers and their situations individually, and we’re not going to discuss specifics,” he said.

A handful of users have apparently been able to go back to unlimited plans after switching, for one reason or another, to limited plans. However, it’s hard to say whether AT&T will be doing this en masse to keep iPhone users from defecting to Verizon.

I’ve switched to Sprint and Verizon for Android devices when the iPhone 4 was released, but kept my AT&T line active. However, I removed the iPhone data plan and text messaging features on it. When I returned to AT&T in September and purchased an iPhone 4, the customer service rep in the store was able to reactive my unlimited data plan even though new purchases – mine wasn’t considered an upgrade at that point – were supposed to fetch the limited data plans. It was a pleasant surprise, so it may be possible for other users to do the same.

Since AT&T is apparently taking this on a case-by-case basis, and won’t comment on its future plans regarding unlimited data packages, it couldn’t hurt to try.